Simulated Benefits of Green Infrastructure for Urban Stormwater Management under Climate Change in Different Hydroclimatic and Archetypal Urban Settings

Abstract:

Climate change could significantly alter the occurrence and management of urban stormwater runoff quantity and quality. Responding to this challenge requires an improved understanding of potential changes together with the effectiveness of management responses for reducing impacts under range of potential future climatic conditions. Traditional gray stormwater infrastructure generally uses single-purpose, hard structures including detention basins and storm sewers to dispose of rainwater. Green infrastructure (GI) uses vegetation and soil to manage rainwater where it falls. GI has been gaining in popularity, and has been shown to provide a number of benefits for adapting to climate change including effects on stormwater quantity, quality and carbon and nutrient biogeochemical cycling. Uncertainty remains, however, due to limited understanding of GI performance in different hydroclimatic and urban settings, and in response to changes in climate. In this study we use simulation modeling to assess the impacts of climate change on both gray (wet ponds) and green infrastructure practices (green roofs, swales, bioretention) in different hydroclimatic and urban settings. Simulations were conducted using RHESSYs, a mechanistic, hydrologic and biogeochemical model, for 36 characteristic urban “archetypes” (AUSs) representing different development patterns and GI practices found in typical U.S. cities. Climate change scenarios are based on dynamically and temporally downscaled, mid-21st century climate model output from the North American Regional Climate Change Assessment Program (NARCCAP). Results suggest altered mass and energy inputs will cause changes in performance of these practices for water quantity, water quality, and carbon sequestration that vary across the country. Infrastructure design should take these potential changes into consideration.